Is there a way to test if an ignition switch on an '83 XJS is working properly? (i.e., with a multimeter or something) I think I have a bad switch but wanted to be sure before shelling out $150-

 

It is possible to test it I guess, but first, what is it doing? This kind of gives us an idea where to start checking.

 

As Jamey said, but why not simply clean it with "contact cleaner p/pack" and then try it once more.

It should be removed from the car prior to this, as that solvent is a killer on paint and leather colour.

The solid Brown wire is the 12v HOT, and is the "common" wire for ohms testing. The other 3 White wired with trace, I FORGET, but it is only a choice of 3, and switch position "1" will be one of them and so on, simple again.

The switch can be easily dismantled (do that inside a plastic freezer bag) as there is a spring in there, and although it should NOT spring out, that little guy Murphy is always hanging around, and you will NOT find that sucker if it takes off.

 

Thank you for the ideas/info. To answer the first question, the switch had a funny (new) 'feel' when it was rotated to the start position. Starter stays engaged and energized whenever battery is connected. I figured that I could test for a short or something to indicate if the proper contacts were closing. Just happened all of a sudden...

 

Yep, use an ohm meter, unplug the connector, and connect one lead to the brown wire. Now use the other meter lead to check which wire is the #1 position, then the #2 position, and then the #3 position.

#1 is accessories.
#2 is Ignition.
#3 is Start, and is the spring loaded position.

I would also be checking the starter relay, it may have the contacts "welded" together, which sounds more likely than the switch at this moment.

Yes, the switches do play up, but so do the relays.

 

Perfect! Thanks and will update